1. Technical Field
The invention relates to methods and materials involved in culturing Anaplasma species.
2. Background Information
Anaplasma phagocytophilum and Anaplasma marginale are obligate intracellular, tick-borne rickettsial pathogens of humans and animals in North America, Europe, Australia, and Africa.
A. phagocytophilum (formerly known as “HGE agent,” Ehrlichia equi, or E. phagocytophila) causes disease in humans, horses, small and large ruminants, dogs, and cats. A. phagocytophilum infections produce an acute, febrile illness accompanied by appearance of the microbes in white blood cells (specifically neutrophil granulocytes, as well as their precursors in the bone marrow), a reduction in the number of all blood cell types (“pancytopenia”), nausea, and confusion. Death occurs in about 5% of human patients if not treated promptly with tetracycline antibiotics. Diagnosis during the acute stage is difficult due to the absence of significant amounts of specific antibodies at that time, and a vaccine is not yet available. Recently, the causative agent has been isolated in cell lines of both human (the promyelocytic human leukemia cell line HL-60) and vector tick (the Ixodes scapularis cell lines ISE6 and IDE8) origin (See Munderloh et al., 1996, J. Clin. Microbiol., 34:664-670; and Munderloh et al., 1999, J. Clin. Microbiol., 37:2518-2524).
A. marginale is only known to infect red blood cells in ruminants, specifically cattle, often being referred to in the literature as an obligate intraerythrocytic pathogen. The disease is characterized by anemia, weakness, loss of milk production, retarded growth, abortion, and, in severe cases, death. The continuous propagation of this microbe in tick cell culture using the I. scapularis cell line IDE8 has been reported (Munderloh et al., 1996, J. Med. Ent., 33:656-664). Despite their availability, tick cell-based cell culture systems have proven difficult to use for many research laboratories in industry and academia.